EP2183253B1

EP2183253B1 - Thieno-pyridine derivatives as mek inhibitors

Info

Publication number: EP2183253B1
Application number: EP08775964.3A
Authority: EP
Inventors: James Andrew Johnson; Daniel Christopher Brookings; Martin Clive Hutchings; Barry John Langham; Judi Charlotte Neuss
Original assignee: UCB Pharma SA
Current assignee: UCB Pharma SA
Priority date: 2007-07-23
Filing date: 2008-07-16
Publication date: 2013-12-18
Anticipated expiration: 2028-07-16
Also published as: US8350037B2; EP2183253A1; WO2009013462A1; US20100179124A1; GB0714384D0

Abstract

A series of thieno[2,3-b]pyridine derivatives which are substituted in the 2-position by a substituted anilino moiety, being selective inhibitors of human MEK (MAPKK) enzymes, are accordingly of benefit in medicine, for example in the treatment of inflammatory, autoimmune, cardiovascular, proliferative (including oncological) and nociceptive conditions.

Description

The present invention relates to a class of thieno-pyridine derivatives and to their use in therapy. More particularly, the invention is concerned with thieno[2,3-b]pyridine derivatives which are substituted in the 2-position by a substituted anilino moiety. These compounds are selective inhibitors of MEK (MAPKK) enzymes, and are accordingly of benefit as pharmaceutical agents, especially in the treatment of adverse inflammatory, autoimmune, cardiovascular, proliferative (including oncological) and nociceptive conditions.
MEK enzymes are implicated in a variety of physiological and pathological functions that are believed to be operative in a range of human diseases. These functions are summarised in paragraphs [0004] and [0005] of US 2005/0049276 A1 .
The compounds of use in the present invention, being potent and selective MEK inhibitors, are therefore beneficial in the treatment and/or prevention of various human ailments. These include autoimmune and inflammatory disorders such as rheumatoid arthritis, osteoarthritis, multiple sclerosis, asthma, inflammatory bowel disease, psoriasis and transplant rejection; cardiovascular disorders including thrombosis, cardiac hypertrophy, hypertension, and irregular contractility of the heart (e.g. during heart failure); proliferative disorders such as restenosis, and oncological conditions including leukaemia, glioblastoma, lymphoma, melanoma, and human cancers of the liver, bone, skin, brain, pancreas, lung, breast, stomach, colon, rectum, prostate, ovary and cervix; and pain and nociceptive disorders, including chronic pain and neuropathic pain.
In addition, the compounds of use in the present invention may be beneficial as pharmacological standards for use in the development of new biological tests and in the search for new pharmacological agents. Thus, the compounds of use in this invention may be useful as radioligands in assays for detecting compounds capable of binding to human MEK enzymes.
MEK inhibitors based on a fused bicyclic aromatic ring system attached to a substituted anilino moiety are known from the art. Examples of relevant publications include WO 2005/051906 , WO 2005/023251 , US-A-2005/0049276 , WO 2005/009975 , WO 03/077914 and WO 03/077855 .
WO 2005/023818 describes a broad-ranging class of compounds based on a fused bicyclic aromatic ring system, which generically encompasses thieno-pyridine derivatives attached to a substituted anilino moiety but nowhere specifically discloses any precise compound of this type. No discrete pharmacological activity, in terms of an identifiable pharmacological mechanism, is ascribed to the compounds described therein, but they are nevertheless stated to be useful inter alia in the treatment of cell proliferative diseases such as cancer. US-A-2003/0220365 is also of relevance in a related context.
Nowhere in the prior art publications acknowledged above, however, is there the precise disclosure of a class of thieno[2,3-b]pyridine derivatives attached at the 2-position to a substituted anilino moiety. It has now been found that such compounds are particularly valuable as selective inhibitors of MEK enzymes.
The compounds of the present invention are potent and selective MEK inhibitors having a binding affinity (IC₅₀) for the human MEK1 and/or MEK2 enzyme of 50 µM or less, generally of 20 µM or less, usually of 5 µM or less, typically of 1 µM or less, suitably of 500 nM or less, ideally of 100 nM or less, and preferably of 20 nM or less (the skilled person will appreciate that a lower IC₅₀ figure denotes a more active compound). The compounds of the invention may possess at least a 10-fold selective affinity, typically at least a 20-fold selective affinity, suitably at least a 50-fold selective affinity, and ideally at least a 100-fold selective affinity, for the human MEK1 and/or MEK2 enzyme relative to other human kinases.
The present invention provides a compound of formula (1), or a pharmaceutically acceptable salt, solvate or N-oxide thereof:
wherein

R¹ represents hydrogen, halogen or C_1-6 alkyl;
R² represents halogen or C_1-6 alkyl;
R³ represents -SO₂NR^bR^c; and
R^b and R^c, when taken together with the nitrogen atom to which they are both attached, represent azetidin-1-yl, pyrrolidin-1-yl, piperidin-1-yl, morpholin-4-yl, thiomorpholin-4-yl, piperazin-1-yl, homopiperidin-1-yl, homomorpholin-4-yl or homopiperazin-1-yl, any of which groups may be optionally substituted by one or more substituents selected from C_1-6 alkyl, hydroxy, hydroxy(C_1-6)alkyl, C_1-6 alkoxy, C_1-6 alkoxy(C_1-6)alkyl, amino(C_1-6)alkyl, (amino)(hydroxy)(C_1-6)alkyl, halogen, oxo, C_2-6 alkylcarbonyl, carboxy, carboxy(C_1-6)alkyl, C_2-6 alkoxycarbonyl, C_2-6 alkoxycarbonyl-(C_1-6)alkyl, di(C_1-6)alkylhydrazinylcarbonyl, amino, C_1-6 alkylamino, di(C_1-6)alkylamino, C_2-6 alkylcarbonylamino, C_2-6 alkoxycarbonylamino, C_2-6 alkoxycarbonylamino(C_1-6)-alkyl, C_2-6 alkoxycarbonyl(C_1-6)alkylamino(C_1-6)alkyl, aminocarbonylamino, aminocarbonyl, C_1-6 alkylaminocarbonyl, di(C_1-6)alkylaminocarbonyl, aminosulfonyl, C_1-6 alkylsulfonyl and C_1-6 alkylaminocarbonyl(C_1-6)alkyl.

Co-pending international patent application no. PCT/GB2007/000310, published on 9 August 2007 as WO 2007/088345 , describes a class of compounds of formula (I) as depicted above, and pharmaceutically acceptable salts, solvates and N-oxides thereof, as MEK inhibitors. Substituent R³ as defined therein, however, differs in all respects from substituent R³ as defined above.
For use in medicine, the salts of the compounds of formula (I) will be pharmaceutically acceptable salts. Other salts may, however, be useful in the preparation of the compounds of the invention or of their pharmaceutically acceptable salts. Suitable pharmaceutically acceptable salts of the compounds of this invention include acid addition salts which may, for example, be formed by mixing a solution of the compound of the invention with a solution of a pharmaceutically acceptable acid such as hydrochloric acid, sulphuric acid, methanesulphonic acid, fumaric acid, maleic acid, succinic acid, acetic acid, benzoic acid, citric acid, tartaric acid or phosphoric acid. Furthermore, where the compounds of the invention carry an acidic moiety, e.g. carboxy, suitable pharmaceutically acceptable salts thereof may include alkali metal salts, e.g. sodium or potassium salts; alkaline earth metal salts, e.g. calcium or magnesium salts; and salts formed with suitable organic ligands, e.g. quaternary ammonium salts.
The present invention includes within its scope solvates of the compounds of formula (I) above. Such solvates may be formed with common organic solvents, e.g. hydrocarbon solvents such as benzene or toluene; chlorinated solvents such as chloroform or dichloromethane; alcoholic solvents such as methanol, ethanol or isopropanol; ethereal solvents such as diethyl ether or tetrahydrofuran; or ester solvents such as ethyl acetate. Alternatively, the solvates of the compounds of formula (I) may be formed with water, in which case they will be hydrates.
Suitable alkyl groups which may be present on the compounds of the invention include straight-chained and branched C_1-6 alkyl groups, for example C_1-4 alkyl groups. Typical examples include methyl and ethyl groups, and straight-chained or branched propyl, butyl and pentyl groups. Particular alkyl groups include methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl and 2,2-dimethylpropyl. Derived expressions such as "C_1-6 alkoxy" and "C_1-6 alkylamino" are to be construed accordingly.
The term "halogen" as used herein is intended to include fluorine, chlorine, bromine and iodine atoms.
Where the compounds of formula (I) have one or more asymmetric centres, they may accordingly exist as enantiomers. Where the compounds of the invention possess two or more asymmetric centres, they may additionally exist as diastereomers. The invention is to be understood to extend to all such enantiomers and diastereomers, and to mixtures thereof in any proportion, including racemates. Formula (I) and the formulae depicted hereinafter are intended to represent all individual stereoisomers and all possible mixtures thereof, unless stated or shown otherwise. In addition, compounds of formula (I) may exist as tautomers, for example keto (CH₂C=O)-enol (CH=CHOH) tautomers. Formula (I) and the formulae depicted hereinafter are intended to represent all individual tautomers and all possible mixtures thereof, unless stated or shown otherwise.
In one embodiment, R¹ represents hydrogen. In another embodiment, R¹ represents halogen, particularly fluoro or chloro, especially fluoro. In a further embodiment, R¹ represents C_1-6 alkyl, especially methyl.
Typically, R¹ is fluoro.
In one embodiment, R² represents halogen, especially bromo or iodo. In another embodiment, R² represents C_1-6 alkyl, especially methyl.
In one specific embodiment, R² is bromo. In another specific embodiment, R² is iodo.
Suitably, the cyclic moiety -NR^bR^c may be unsubstituted, or substituted by one or more substituents, typically by one or two substituents. In one embodiment, the cyclic moiety -NR^bR^c is unsubstituted. In another embodiment, the cyclic moiety -NR^bR^c is monosubstituted. In a further embodiment, the cyclic moiety -NR^bR^c is disubstituted.
Examples of particular substituents on the cyclic moiety -NR^bR^c include methyl, hydroxy, hydroxymethyl, 2-hydroxyethyl, methoxy, methoxymethyl, aminomethyl, 2-amino-3-hydroxypropyl, fluoro, oxo, acetyl, carboxy, carboxymethyl, methoxycarbonyl, ethoxycarbonyl, tert-butoxycarbonyl, ethoxycarbonylmethyl, dimethylhydrazinyl-carbonyl, amino, methylamino, 1,3-dimethylbutylamino, dimethylamino, acetylamino, tert-butoxycarbonylamino, tert-butoxycarbonylaminomethyl, ethoxycarbonylmethylaminomethyl, ethoxycarbonylethylaminomethyl, aminocarbonylamino, aminocarbonyl, ethylaminocarbonyl, diethylaminocarbonyl, aminosulfonyl, methylsulfonyl and methylaminocarbonylmethyl.
Examples of favoured substituents on the cyclic moiety -NR^bR^c include hydroxy, amino, amino(C_1-6)alkyl, C_2-6 alkoxycarbonylamino and C_2-6 alkoxycarbonyl(C_1-6)alkylamino(C_1-6)alkyl.
Examples of specific substituents on the cyclic moiety -NR^bR^c include hydroxy, amino, aminomethyl, tert-butoxycarbonylamino, ethoxycarbonylmethylaminomethyl and ethoxycarbonylethylaminomethyl.
Particular values for the cyclic moiety -NR^bR^c include azetidin-1-yl, pyrrolidin-1-yl and piperazin-1-yl, any of which groups may be optionally substituted by one or more substituents.
Specific values of the cyclic moiety -NR^bR^c include 3-hydroxyazetidin-1-yl, 3-aminoazetidin-1-yl, 3-(aminomethyl)azetidin-1-yl, 3-(aminomethyl)-3-hydroxyazetidin-1-yl, 3-(tert-butoxycarbonylamino)azetidin-1-yl, 3-(ethoxycarbonylmethylaminomethyl)-azetidin-1-yl, 3-(ethoxycarbonylethylaminomethyl)azetidin-1-yl, pyrrolidin-1-yl, 3-hydroxypyrrolidin-1-yl, 3-aminopyrrolidin-1-yl, 3-(tert-butoxycarbonylamino)pyrrolidin-1-yl and piperazin-1-yl.
A particular sub-group of compounds according to the invention is represented by the compounds of formula (II), and pharmaceutically acceptable salts, solvates and N-oxides thereof:
wherein
R¹² represents halogen; and
R³ is as defined above.
In one specific embodiment, R¹² is bromo. In another specific embodiment, R¹² is iodo.
Specific novel compounds in accordance with the present invention include each of the compounds whose preparation is described in the accompanying Examples, and pharmaceutically acceptable salts and solvates thereof.
The present invention also provides a pharmaceutical composition which comprises a compound of formula (I) as defined above, or a pharmaceutically acceptable salt, solvate or N-oxide thereof, in association with one or more pharmaceutically acceptable carriers.
Pharmaceutical compositions according to the invention may take a form suitable for oral, buccal, parenteral, nasal, topical, ophthalmic or rectal administration, or a form suitable for administration by inhalation or insufflation.
For oral administration, the pharmaceutical compositions may take the form of, for example, tablets, lozenges or capsules prepared by conventional means with pharmaceutically acceptable excipients such as binding agents (e.g. pregelatinised maize starch, polyvinylpyrrolidone or hydroxypropyl methyl cellulose); fillers (e.g. lactose, microcrystalline cellulose or calcium hydrogenphosphate); lubricants (e.g. magnesium stearate, talc or silica); disintegrants (e.g. potato starch or sodium glycollate); or wetting agents (e.g. sodium lauryl sulphate). The tablets may be coated by methods well known in the art. Liquid preparations for oral administration may take the form of, for example, solutions, syrups or suspensions, or they may be presented as a dry product for constitution with water or other suitable vehicle before use. Such liquid preparations may be prepared by conventional means with pharmaceutically acceptable additives such as suspending agents, emulsifying agents, non-aqueous vehicles or preservatives. The preparations may also contain buffer salts, flavouring agents, colouring agents or sweetening agents, as appropriate.
Preparations for oral administration may be suitably formulated to give controlled release of the active compound.
For buccal administration, the compositions may take the form of tablets or lozenges formulated in conventional manner.
The compounds of formula (I) may be formulated for parenteral administration by injection, e.g. by bolus injection or infusion. Formulations for injection may be presented in unit dosage form, e.g. in glass ampoules or multi-dose containers, e.g. glass vials. The compositions for injection may take such forms as suspensions, solutions or emulsions in oily or aqueous vehicles, and may contain formulatory agents such as suspending, stabilising, preserving and/or dispersing agents. Alternatively, the active ingredient may be in powder form for constitution with a suitable vehicle, e.g. sterile pyrogen-free water, before use.
In addition to the formulations described above, the compounds of formula (I) may also be formulated as a depot preparation. Such long-acting formulations may be administered by implantation or by intramuscular injection.
For nasal administration or administration by inhalation, the compounds according to the present invention may be conveniently delivered in the form of an aerosol spray presentation for pressurised packs or a nebuliser, with the use of a suitable propellant, e.g. dichlorodifluoromethane, fluorotrichloromethane, dichlorotetrafluoroethane, carbon dioxide or other suitable gas or mixture of gases.
The compositions may, if desired, be presented in a pack or dispenser device which may contain one or more unit dosage forms containing the active ingredient. The pack or dispensing device may be accompanied by instructions for administration.
For topical administration the compounds according to the present invention may be conveniently formulated in a suitable ointment containing the active component suspended or dissolved in one or more pharmaceutically acceptable carriers. Particular carriers include, for example, mineral oil, liquid petroleum, propylene glycol, polyoxyethylene, polyoxypropylene, emulsifying wax and water. Alternatively, the compounds according to the present invention may be formulated in a suitable lotion containing the active component suspended or dissolved in one or more pharmaceutically acceptable carriers. Particular carriers include, for example, mineral oil, sorbitan monostearate, polysorbate 60, cetyl esters wax, cetearyl alcohol, benzyl alcohol, 2-octyldodecanol and water.
For ophthalmic administration the compounds according to the present invention may be conveniently formulated as microionized suspensions in isotonic, pH-adjusted sterile saline, either with or without a preservative such as a bactericidal or fungicidal agent, for example phenylmercuric nitrate, benzylalkonium chloride or chlorhexidine acetate. Alternatively, for ophthalmic administration compounds may be formulated in an ointment such as petrolatum.
For rectal administration the compounds according to the present invention may be conveniently formulated as suppositories. These can be prepared by mixing the active component with a suitable non-irritating excipient which is solid at room temperature but liquid at rectal temperature and so will melt in the rectum to release the active component. Such materials include, for example, cocoa butter, beeswax and polyethylene glycols.
The quantity of a compound of the invention required for the prophylaxis or treatment of a particular condition will vary depending on the compound chosen and the condition of the patient to be treated. In general, however, daily dosages may range from around 10 ng/kg to 1000 mg/kg, typically from 100 ng/kg to 100 mg/kg, e.g. around 0.01 mg/kg to 40 mg/kg body weight, for oral or buccal administration, from around 10 ng/kg to 50 mg/kg body weight for parenteral administration, and from around 0.05 mg to around 1000 mg, e.g. from around 0.5 mg to around 1000 mg, for nasal administration or administration by inhalation or insufflation.
The compounds of formula (I) above wherein R³ represents -SO₂NR^bR^c may be prepared by a process which comprises reacting a compound of formula H-NR^bR^c with a compound of formula (III):
wherein R¹ and R² are as defined above.
The reaction is conveniently effected in a suitable solvent, e.g. dichloromethane, typically under basic conditions, e.g. in the presence of an organic base such as pyridine or triethylamine.
The intermediates of formula (III) may suitably be prepared by reacting a compound of formula (IV):
wherein R¹ and R² are as defined above; with chlorosulphonic acid; followed by treatment with pentafluorophenol, typically in the presence of an organic base such as pyridine.
In an alternative procedure, the compounds of formula (I) above wherein R³ represents -SO₂NR^bR^c may be prepared by a process which comprises reacting a compound of formula (IV) as defined above with chlorosulphonic acid; followed by treatment with a compound of formula H-NR^bR^c. The reaction is conveniently effected in an inert solvent, e.g. dichloromethane.
The intermediates of formula (IV) may suitably be prepared by decarboxylating a compound of formula (V):
wherein R¹ and R² are as defined above.
Decarboxylation is conveniently effected by heating compound (V), typically at the reflux temperature, in an inert solvent such as toluene.
The intermediates of formula (V) above may suitably be prepared by reacting a compound of formula (VI) with a compound of formula (VII):
wherein R¹ and R² are as defined above, and L¹ represents a suitable leaving group.
The leaving group L¹ is typically a halogen atom, e.g. chloro.
The reaction is conveniently effected, at an elevated temperature if necessary, in a suitable solvent, e.g. tetrahydrofuran, typically under basic conditions, e.g. in the presence of lithium diisopropylamide.
The intermediates of formula (VII) above may be prepared by reacting a compound of formula (VIII):
wherein R¹ and R² are as defined above; with thiophosgene.
The reaction is conveniently effected in a suitable solvent, typically a mixture of chloroform and water.
Where they are not commercially available, the starting materials of formula (VI) and (VIII) may be prepared by methods analogous to those described in the accompanying Examples, or by standard methods well known from the art.
It will be understood that any compound of formula (I) initially obtained from any of the above processes may, where appropriate, subsequently be elaborated into a further compound of formula (I) by techniques known from the art. By way of example, a compound of formula (I) wherein R³ contains a nitrogen atom to which a tert-butoxycarbonyl (BOC) group is attached may be converted into the corresponding compound wherein R³ contains an N-H functionality by treatment with an acid, e.g. a mineral acid such as hydrochloric acid, or an organic acid such as trifluoroacetic acid. A compound of formula (I) wherein R³ contains a nitrogen atom to which a benzyloxycarbonyl group is attached may be converted into the corresponding compound wherein R³ contains an N-H functionality by treatment with trifluoroacetic acid. A compound of formula (I) wherein R² contains an N-H functionality may be converted into the corresponding compound wherein R³ contains a nitrogen atom to which an ethoxycarbonylmethyl group is attached by treatment with ethyl chloroacetate or ethyl bromoacetate, typically in the presence of an organic base such as triethylamine or N,N-diisopropylethylamine; the resulting compound may then be converted into the corresponding compound wherein R³ contains a nitrogen atom to which a carboxymethyl group is attached by treatment with an alkaline reagent such as sodium hydroxide, typically in an aqueous solution of a lower alkanol such as ethanol. A compound of formula (I) wherein R³ contains an N-H functionality may be converted into the corresponding compound wherein R³ contains a nitrogen atom to which an ethoxycarbonylethyl group is attached by treatment with ethyl acrylate, typically in the presence of an organic base such as N,N-diisopropylethylamine. In general, a compound of formula (I) wherein R³ contains an ester moiety, e.g. a C_1-6 alkoxycarbonyl group such as methoxycarbonyl or ethoxycarbonyl, may be converted into the corresponding compound wherein R³ contains a carboxy (-CO₂H moiety by treatment with an alkali metal hydroxide, e.g. sodium hydroxide or lithium hydroxide. A compound of formula (I) wherein R³ contains a 2,2-dimethyl-[1,3]dioxolan-4-ylmethyl moiety may be converted into the corresponding compound wherein R³ contains a 2,3-dihydroxypropyl moiety by treatment with a mineral acid such as hydrochloric acid. The pyridine-N-oxide derivative of a compound of formula (I) may be converted into the corresponding compound of formula (I) by treatment with triphenyl phosphine and phosphorus trichloride.
Where a mixture of products is obtained from any of the processes described above for the preparation of compounds according to the invention, the desired product can be separated therefrom at an appropriate stage by conventional methods such as preparative HPLC; or column chromatography utilising, for example, silica and/or alumina in conjunction with an appropriate solvent system.
Where the above-described processes for the preparation of the compounds according to the invention give rise to mixtures of stereoisomers, these isomers may be separated by conventional techniques. In particular, where it is desired to obtain a particular enantiomer of a compound of formula (I) this may be produced from a corresponding mixture of enantiomers using any suitable conventional procedure for resolving enantiomers. Thus, for example, diastereomeric derivatives, e.g. salts, may be produced by reaction of a mixture of enantiomers of formula (I), e.g. a racemate, and an appropriate chiral compound, e.g. a chiral base. The diastereomers may then be separated by any convenient means, for example by crystallisation, and the desired enantiomer recovered, e.g. by treatment with an acid in the instance where the diastereomer is a salt. In another resolution process a racemate of formula (I) may be separated using chiral HPLC. Moreover, if desired, a particular enantiomer may be obtained by using an appropriate chiral intermediate in one of the processes described above. Alternatively, a particular enantiomer may be obtained by performing an enantiomer-specific enzymatic biotransformation, e.g. an ester hydrolysis using an esterase, and then purifying only the enantiomerically pure hydrolysed acid from the unreacted ester antipode. Chromatography, recrystallisation and other conventional separation procedures may also be used with intermediates or final products where it is desired to obtain a particular geometric isomer of the invention.
During any of the above synthetic sequences it may be necessary and/or desirable to protect sensitive or reactive groups on any of the molecules concerned. This may be achieved by means of conventional protecting groups, such as those described in Protective Groups in Organic Chemistry, ed. J.F.W. McOmie, Plenum Press, 1973; and T.W. Greene & P.G.M. Wuts, Protective Groups in Organic Syntheses, John Wiley & Sons, 3rd edition, 1999. The protecting groups may be removed at any convenient subsequent stage utilising methods known from the art.
The following Examples illustrate the preparation of compounds according to the invention.
The compounds in accordance with this invention potently inhibit the activity of human MEK enzyme.

In vitro MEK assay

MEK1 activity was measured in a cascade assay initiated by active Raf, via activation of MEK, Erk2 and subsequent phosphorylation of fluorescein-labelled Erk-tide substrate in an assay based on fluorescence polarisation (IMAP). The assay was carried out in 20mM Tris + 5mM MgCl₂ + 2mM DL-dithiothreitol + 0.01 % Tween 20 pH 7.2, containing 1.5nM unactive MEK, 100nM unactive Erk and 200nM Erk-tide (all concentrations are final concentrations). Compounds, or DMSO controls, were tested at a final concentration of 2% DMSO, and the assay initiated in the presence of 5µM ATP by addition of 1.25nM active Raf in assay buffer. After 20 min at r.t., stop solution was added followed by IMAP binding beads, the assay mixture was then incubated for 90 min at r.t. (with shaking) and then read on a Molecular Devices LJL HT reader.
When tested in the above assay, the compounds of the accompanying Examples were all found to inhibit human MEK enzyme with IC₅₀ values of 10 µM or better.

EXAMPLES

Abbreviations used

EtOAc - ethyl acetate	DMSO - dimethylsulphoxide
THF - tetrahydrofuran	DCM - dichloromethane
Et₂O/ether - diethyl ether	CDCl₃ - deuterochloroform
MeOH - methanol	MeCN - acetonitrile
EtOH - ethanol	ES - electrospray
DMF - N,N-dimethylformamide	HOBT - 1-hydroxybenzotriazole
SiO₂ - silica	NMM - N-methylmorpholine
h - hour(s)	min - minute(s)
r.t. - room temperature	aq - aqueous
sat. - saturated	RT - retention time
conc. - concentrated	BOC - tert-butoxycarbonyl
TFA - trifluoroacetic acid
EDC - 1-(3-dimethylaminopropyl)-3-carbodiimide hydrochloride
PyBrOP - (bromo)tris(pyrrolidino)phosphonium hexafluorophosphate
Dess-Martin periodinane - 1,1,1-tris(acetyloxy)-1,1-dihydro-1,2-benziodoxol-3(1H)-one

All NMR spectra were obtained either at 300 MHz or 400 MHz.
Compounds were named with the aid of ACD Labs Name (v. 7.0) supplied by Advanced Chemical Development, Toronto, Canada.

Standard LCMS method

The LC-MS system used comprises a Waters Alliance 2795 HT quaternary HPLC, Waters 996 Photo Diode Array (PDA) detector and Waters ZQ 4000 single quadrupole mass spectrometer. The ZQ can acquire data simultaneously in positive and negative electrospray ionisation modes.

ZQ Mass Spectrometer

Capillary	3.5kV	Cone	50V
Extractor	2V	Source Temp	80°C
Desolvation Temp	200°C	Cone Gas	150 L/h
Desolvation Gas	250 L/h	Multiplier	650V

Data were acquired in a full scan from 100 to 1000 m/z.

Scan duration 0.80 s

Interscan delay 0.20 s

HPLC

Analytical reverse phase separation was carried out on a Gemini C18 from Phenomenex 50 x 4.6 mm with 5 µm silica.

Injection Volume 5 µL

UVdata 240 to 400 nm

Sample Temperature 20°C

Column Temperature 30°C

Flow Rate 0.9 mL/min

Split to ZQ -0.40 mL/min

Solvent A: 90% 10mM NH₄HCO₂ in water / 0.1 % formic acid /10% CH₃CN
Solvent B: 90% CH₃CN / 0.1 % formic acid /10% 10mM NH₄HCO₂ in water
Solvent C: 90% 10mM NH₄HCO₂ in water /0.1% ammonia / 10% CH₃CN
Solvent D: 90% CH₃CN /10% 10mM NH₄HCO₂ in water / 0.1% ammonia

Gradient Program

For method 5_95_pH=3

Time (min) A% B% Flow Curve

0.00 95.0 5.0 0.900 1

2.00 5.0 95.0 0.900 6

4.00 5.0 95.0 0.900 6

5.00 95.0 5.0 0.900 6
For method 5_95_pH=10

Time (min) A% B% Flow Curve

0.00 95.0 5.0 0.900 1

2.00 5.0 95.0 0.900 6

4.00 5.0 95.0 0.900 6

5.00 95.0 5.0 0.900 6

Preparative UV-HPLC

The LC system comprises a Waters 2525 quaternary pump, a Waters 996 Photo Diode Array (PDA) detector, a Waters 2700 sample manager, a Column Fluidics Organiser and a Waters Fraction Collector operating in reverse phase at one of two pH systems.

Low pH system (approximately pH 3.2)

The reverse phase separation was carried out on a Luna C18 from Phenomenex 100 x 21.2 mm with 5 µm silica.

Injection Volume 500 µL

UV data 254 nm

Flow Rate 20 mL/min

Solvent A 90% water / 10% CH₃CN / 0.1 % formic acid

Solvent B 90% CH₃CN / 10% water / 0.1 % formic acid

High pH system (approximately pH 9.5)

The reverse phase separation was carried out on a Gemini C18 from Phenomenex 150 x 21.2 mm with 10 µm silica.

Injection Volume 500 µL

UV data 254 nm

Flow Rate 20 mL/min

Solvent C 90% 10mM NH₄HCO₂ in water / 0.1% ammonia / 10% CH₃CN

Solvent D 90% CH₃CN / 10% 10mM NH₄HCO₂ in water / 0.1% ammonia
Typical gradient profiles are described below:

Gradient Program for Low pH Method

Time	A%	B%	C%	D%	Flow	Curve
0.00	95.0	5.0	0.0	0.0	20	1
9.00	5.0	95.0	0.0	0.0	20	6
11.00	5.0	95.0	0.0	0.0	20	6
11.50	95.0	5.0	0.0	0.0	20	6
12.00	95.0	5.0	0.0	0.0	20	6

Gradient Program for High pH Method

Time	A%	B%	C%	D%	Flow	Curve
0.00	0.0	0.0	95.0	5.0	20	1
9.00	0.0	0.0	5.0	95.0	20	6
11.00	0.0	0.0	5.0	95.0	20	6
11.50	0.0	0.0	95.0	5.0	20	6
12.00	0.0	0.0	95.0	5.0	20	6

INTERMEDIATE 1

2-Chloro-3-(chloromethyl)pyridine

To a 500 mL, round-bottom, 3-necked flask equipped with dropping funnel and magnetic stirrer and set for reflux was prepared a solution of 2-chloro-3-(hydroxymethyl)-pyridine (25.0 g, 174 mmol) in DCM (250 mL) under positive nitrogen atmosphere. The solution was cooled to 10°C and thionyl chloride (31.0 g) was added dropwise over 25 minutes (exothermic). The reaction was then heated to reflux for 90 minutes, at which point the reaction was deemed complete by HPLC. The reaction mixture was cooled below boiling point and the equipment set for distillation. A total of 110 mL of DCM was initially removed and replenished with fresh DCM (110 mL), followed by another 80 mL of DCM before cooling the solution to 5-10°C. The acidic mixture was treated with a saturated solution of sodium bicarbonate (3 volumes) to pH 10. The lower organic phase was separated and the aqueous phase extracted with DCM (2 volumes). The organic phases were gathered, dried on sodium sulfate, filtered and concentrated in vacuo to afford the title compound as a pale yellow oil in excellent purity and yield (24.8 g, 88%). δ_H (d₆-DMSO, 300 MHz) 8.45 (1H, dd), 8.10 (1H, dd), 7.50 (1H, dd), 4.85 (2H, s). LCMS (ES)⁺ RT 3.00 min, m/e 162.1.

INTERMEDIATE 2

(2-Chloropyridin-3-yl)acetonitrile

In a 3 L reactor, set for reflux under positive nitrogen pressure and using a bleach scrubber, was prepared a solution of potassium cyanide (68.32 g, 1.04M) in EtOH (136 mL) and water (255 mL). The mixture was heated to reflux, at which point a solution of 2-chloro-3-(chloromethyl)pyridine (Intermediate 1; 170.0 g, 1.04M) in EtOH (170 mL) was added dropwise over 30 minutes. The whole mixture was maintained at reflux for a further 150 minutes. The mixture was then allowed to cool just below boiling point and the equipment set for distillation. A total of 8.5 volumes of EtOH were removed. On cooling, half a volume of water was added. At a temperature of 40°C, the solution was seeded and crystallised instantaneously. The thick beige slurry was allowed to cool to ambient temperature and then to 0°C. This mixture was filtered, rinsed with cold water (2 vols) and dried at 45°C in a vacuum oven overnight. The title compound was afforded as a beige solid in excellent yield and purity (126.9 g, 80%). δ_H (d₆-DMSO, 300 MHz) 8.45 (1H, dd), 8.00 (1H, dd), 7.50 (1H, dd), 4.15 (2H, s). LCMS (ES)⁺ RT 2.15 min, m/e 153.01 & 155.01 (M+1 & M+3, Product).

INTERMEDIATE 3

(2-Chloropyridin-3-yl)acetic acid

To a 2 L reactor, set for reflux, was stirred a pre-prepared 15% w/w solution of sodium hydroxide (5 vols) to which was added (2-chloropyridin-3-yl)acetonitrile (Intermediate 2; 276.4 g, 1.81M). The beige suspension was heated to reflux for 30 minutes, at which point the reaction was deemed complete by HPLC. The brown solution was then cooled to 0-5°C and acidified to pH 1 with conc. HCl while keeping the temperature below 10°C, using concentrated hydrochloric acid (1.8 vols). An off-white solid precipitated and was left to mature for another hour before filtration. Once dried, the material was recrystallised from propan-2-ol (4 vols) to afford the title compound as an off-white material in excellent yield and purity (280.3 g, 90%). δ_H (d₆-DMSO, 300 MHz) 12.70 (1H, s), 8.35 (1H, dd), 7.85 (1H, dd), 7.40 (1H, dd), 4.25 (2H, s). LCMS (ES)⁺ RT 1.75 min, m/e 171.99 (M+1, Product).

INTERMEDIATE 4

2-Fluoro-4-iodo-1-isothiocyanatobenzene

Thiophosgene (3.55 ml, 46.4 mmol) was added to a rapidly-stirred mixture of 2-fluoro-4-iodoaniline (10.0 g, 42.2 mmol) in CHCl₃ (200 ml) and water (100 ml). The mixture was stirred at r.t. for 16 h. The organic phase was dried (Na₂SO₄) and concentrated in vacuo to give the title compound as an off-white crystalline solid (11.8 g, quant.). δ_H (DMSO-d₆) 7.87 (1H, dd, J 1.8, 9.5 Hz), 7.63 (1H, ddd, J 1.0, 1.8, 8.4 Hz), 7.25 (1H, dd, J 8.2, 8.4 Hz).

INTERMEDIATE 5

2-[(2-Fluoro-4-iodophenyl)amino]thieno[2,3-b]pyridine-3-carboxylic acid

To a stirred solution of diisopropylamine (35.3 mL, 250 mmol) in anhydrous THF (200 mL) cooled to -15°C was added n-butyllithium (100 mL, 2.5M in hexanes, 250 mmol) slowly such that an internal temperature of between -10 and 0°C was maintained. The resultant mixture was stirred at room temperature for 15 minutes before being cooled to 0°C. The solution of lithium diisopropylamide was added via cannula to a rapidly stirred suspension of (2-chloropyridin-3-yl)acetic acid (Intermediate 3; 21.4 g, 125 mmol) in anhydrous THF (400 mL) at 0°C. The temperature of the reaction mixture was maintained at 0°C over the course of the addition. Upon complete addition of the lithium diisopropylamide solution the resultant bright yellow suspension was stirred at 0°C for 15 minutes. A solution of Intermediate 4 (34.9 g, 125 mmol) in anhydrous THF (200 mL) was then added to the reaction mixture via cannula and the mixture heated to 65°C for 18 hours. The reaction mixture was cooled and the volatiles removed in vacuo. The resultant brown gum was redissolved in THF (200 mL), cooled to 0°C and 10% aqueous acetic acid (500 mL) added slowly. Acetonitrile (-200 mL) was added slowly until a brown solid developed; the solid was isolated by filtration and washed with successive portions of diethyl ether and acetonitrile to give the title compound as a yellow crystalline solid (11.0 g, 21%). δ_H (DMSO-d₆) 8.42 (1H, d, J 6.7 Hz), 8.22 (1H, m), 7.73 (1H, m), 7.61 (1H, m), 7.46 (1H, t, J 8.6 Hz), 7.35-7.31 (1H, m). Exchangeable protons were not observed. LCMS (pH 10) RT 1.82 minutes, ES⁺ 415 (M+H)⁺, ES^- 413 (M-H)^-.

INTERMEDIATE 6

N-(2-Fluoro-4-iodophenyl)thieno[2,3-b]pyridin-2-amine

A suspension of Intermediate 5 (3 g, 7.2 mmol) in toluene (50 mL) was heated at reflux for 18 hours. After this time the solvent was removed in vacuo to afford the title compound as a pale brown solid (2.7 g, quant.). δ_H (CDCl₃) 8.42 (1H, dd J 1.6, 4.7 Hz), 7.82 (1H, dd J 1.4, 8.1 Hz), 7.46 (2H, m), 7.27-7.18 (2H, m), 6.77 (1H, s), 6.25 (1H, s). LCMS (pH 10) RT 3.36 minutes, (ES⁺) 371 (M+H)⁺.

INTERMEDIATE 7

Pentafluorophenyl 2-[(2-fluoro-4-iodophenyl)amino]thieno[2,3-b]pyridine-3-sulfonate

A solution of Intermediate 6 (270 mg, 0.73 mmol) in DCM (25 mL) was cooled (acetone/CO₂ bath) before chlorosulfonic acid (0.24 ml, 3.65 mmol) was added dropwise. The mixture was placed in an ice bath and stirred for 5 hours, before pyridine (1.2 mL, 14.6 mmol) and then pentafluorophenol (300 mg, 1.6 mmol) were added. After 18 hours the reaction mixture was partitioned between DCM (100 mL) and water (100 mL). The organic layer was dried (Na₂SO₄) and concentrated in vacuo and after chromatography (SiO₂/DCM) gave the title compound as a white crystalline solid (395 mg. 88%). δ_H (CDCl₃) 8.57 (1H, s), 8.43 (1H, m), 8.15 (1H, m), 7.62 (2H, m), 7.39-7.27 (2H, m). LCMS (pH 3) RT 3.93 minutes, (ES⁺) 617 (M+H)⁺.

INTERMEDIATE 8

tert-Butyl {[1-({2-[(2-fluoro-4-iodophenyl)amino]thieno[2,3-b]pyridin-3-yl}sulfonyl)-azetidin-3-yl]methyl}carbamate

To a solution of Intermediate 7 (190 mg, 0.31 mmol) and pyridine (0.047 mL, 0.60 mmol) in DCM (5 mL) was added azetidin-3-ylmethylcarbamic acid tert-butyl ester (115 mg, 0.62 mmol) and the reaction stirred overnight at ambient temperature. After this time the reaction mixture was diluted with 30 mL of DCM, and washed with 2M HCl (2 x 25 mL) and water (25 mL). After drying (Na₂SO₄) and evaporating in vacuo, the residue was purified by chromatography (SiO₂, 30% EtOAc in DCM) to afford the title compound as a white solid (150 mg, 78%). δ_H (CDCl₃) 9.04 (1H, s), 8.39 (1H, dd, J 1.6, 4.7 Hz), 8.20 (1H, dd, J 1.6, 8.1 Hz), 7.58 (2H, m), 7.40 (1H, m), 7.31 (1H, dd, J 4.8, 8.2 Hz), 4.68 (1H, s), 3.95 (2H, dd, J 8.1, 8.1 Hz), 3.63 (2H, m), 3.25 (2H, m), 2.69 (1H, m), 1.41 (9H, s). LCMS (pH 3) RT 3.51 minutes, (ES⁺) 619 (M+H)⁺.

INTERMEDIATE 9

tert-Butyl 4-({2-[(2-fluoro-4-iodophenyl)amino]thieno[2,3-b]pyridin-3-yl}sulfonyl)piperazine-1-carboxylate

Prepared from Intermediate 6 (200 mg, 0.541 mmol) by the method of Example 2 with N-BOC-piperazine (1.0 g, 1.08 mmol) to give after column chromatography (SiO₂, 20% EtOAc in DCM) the title compound as an off-white solid (60 mg, 18%). δ_H (CDCl₃) 9.00 (1H, s), 8.40 (1H, dd, J 1.4, 4.8 Hz), 8.16 (1H, dd, J 1.6, 8.2 Hz), 7.58 (2H, m), 7.38 (1H, dd, J 8.6, 8.6 Hz), 7.31 (1H, dd, J 4.7, 8.2 Hz), 3.53 (4H, t, J 4.9 Hz), 3.18 (4H, t, J 4.9 Hz), 1.43 (9H, s). LCMS (pH 10) RT 2.91 minutes, (ES⁺) 619 (M+H)⁺.

INTERMEDIATE 10

3-Hydroxy-3-(nitromethyl)azetidine-1-carboxylic acid tert-butyl ester

3-Oxoazetidine-1-carboxylic acid tert-butyl ester (500 mg, 2.9 mmol) was dissolved in ethanol (1.5 mL) and to this was added nitromethane (0.6 mL) and triethylamine (cat.). The reaction was stirred for eighteen hours and the solvent was then removed under reduced pressure to yield the title compound as a white solid (650 mg, 97%). δ_H (d₆-DMSO) 6.42 (1H, s), 4.86 (2H, s), 4.04 (2H, d, J9.2 Hz), 3.75 (2H, d, J9.2 Hz), 1.39 (9H, s). LCMS (ES⁺) RT (pH 10) 1.73 min (M-H)^- 231.

INTERMEDIATE 11

3-(Aminomethyl)-3-hydroxyazetidine trifluoroacetate salt

Intermediate 10 (500 mg, 2.2 mmol) was dissolved in ethanol (40 mL) in a hydrogenation vessel and 10% palladium on charcoal (43 mg) was added. The vessel was charged with hydrogen to 50 psi and heated to 50°C. This was then stirred for 2 h and the catalyst was removed by filtering through a plug of celite. The solvent was removed under reduced pressure to yield a pale yellow oil. The intermediate was purified by chromatography on an amine column using 5% DCM/MeOH as the eluent to afford the BOC-protected amine as an off-white solid (306 mg, 68%). δ_H (d₆-DMSO) 5.50 (1H, s), 3.73 (2H, d, J 8.5 Hz), 3.54 (2H, d, J 8.5 Hz), 2.60 (2H, s), 1.37 (9H, s). Some exchangeable protons were not observed. The intermediate BOC-protected amine was dissolved in DCM (10 mL) and trifluoroacetic acid (1 mL) added. The mixture was stirred for 1 hour at room temperature before the volatiles were removed in vacuo to give the title compound, which was used without further purification.

EXAMPLE 1

N-(2-Fluoro-4-iodophenyl)-3-(pyrrolidin-1-ylsulfonyl)thieno[2,3-b]pyridin-2-amine

To a solution of Intermediate 6 (60 mg, 0.16 mmol) in DCM (5 mL), cooled in a CO₂/acetone bath, was added chlorosulfonic acid (200 mg, 1.72 mmol) dropwise. The reaction mixture was placed in an ice bath and stirred for a further 5 hours. After this time pyrrolidine (250 mg, 3.5 mmol) was slowly added and the reaction stirred for 18 hours at ambient temperature. The reaction mixture was diluted with DCM (25 mL) and washed with water (20 mL), 2M HCl (20 mL) and water (20 mL). The organic phases were dried (Na₂SO₄) and evaporated in vacuo. The product was recrystallised from acetonitrile/water to afford the title compound (30 mg, 37%) as an off-white solid. δ_H (CDCl₃) 9.12 (1H, s), 8.38 (1H, dd, J 4.8, 1.5 Hz), 8.24 (1H, dd, J 8.1, 1.5 Hz), 7.57 (2H, m), 7.40 (2H, m), 3.38 (4H, t, J6.6 Hz), 1.89 (4H, t, J6.6 Hz). LCMS (pH 3) RT 3.95 minutes, (ES⁺) 504 (M+H)⁺.

EXAMPLE 2

3-{[3-(Aminomethyl)azetidin-1-yl]sulfonyl}-N-(2-fluoro-4-iodophenyl)thieno[2,3-b]pyridin-2-amine

Intermediate 8 (140 mg, 0.23mmol) was treated with a 20% solution of TFA in DCM (5 mL). The reaction mixture was stirred for three hours at room temperature, before diluting with 25 mL of DCM and washing with NaHCO₃ solution (25 mL) and then water (25 mL). The organic layer was dried (Na₂SO₄) and evaporated in vacuo to give the title compound as a white powder (89 mg, 75%). δ_H (DMSO-d₆) 8.26 (1H, s), 8.08 (1H, dd, J 1.6, 4.7 Hz), 7.92 (1H, dd, J 1.6, 8.1 Hz), 7.66 (1H, dd, J 1.9, 10.1 Hz), 7.53 (1H, dd, J 2.0, 8.3 Hz), 7.23 (2H, m), 3.92 (2H, t, J 8.2 Hz), 3.65 (2H, m), 2.80 (2H, d, J 7.3 Hz), 2.54 (1H, m). Exchangeable protons were not observed. LCMS (pH 10) RT 2.73 minutes, (ES⁺) 519 (M+H)⁺.

EXAMPLE 3

tert-Butyl[(3R)-1-({2-[(2-fluoro-4-iodophenyl)amino]thieno[2,3-b]pyridin-3-yl}sulfonyl)pyrrolidin-3-yl]carbamate

To a solution of Intermediate 7 (300 mg, 0.48 mmol) and pyridine (0.075 mL, 0.96 mmol) in DCM (5 mL) was added pyrrolidinyl-3(R)-carbamic acid tert-butyl ester (76 mg, 0.96 mmol) and the reaction was stirred overnight at ambient temperature. After this time the reaction mixture was diluted with DCM (35 mL), and washed with 2M HCl (2 x 25 mL) and water (25 mL). The organic phases were dried (Na₂SO₄), filtered and the solvents removed in vacuo to give a crude residue. Purification by column chromatography (SiO₂, 25% EtOAc in DCM) gave the title compound as a white solid (300 mg, 100%). δ_H (CDCl₃) 8.98 (1H, s), 8.30 (1H, dd, J 1.2, 4.6 Hz), 8.10 (1H, dd, J 1.2, 8.1 Hz), 7.50 (2H, m), 7.30 (1H, m), 7.27 (1H, dd, J 4.7, 8.2 Hz), 4.55 (1 H, br s), 4.11 (1H, s), 3.45 (2H, m), 3.20 (2H, m), 2.10 (1H, m), 1.70 (1H, m), 1.33 (9H, s). LCMS (pH 3) RT 3.54 minutes, (ES⁺) 619 (M+H)⁺.

EXAMPLE 4

3-{[(3R)-3-Aminopyrrolidin-1-yl]sulfonyl}-N-(2-fluoro-4-iodophenyl)thieno[2,3-b]pyridin-2-amine

Example 3 (300 mg, 0.48 mmol) was treated with a 20% solution of TFA in DCM (5 mL). The reaction mixture was stirred for three hours at room temperature before being diluted with DCM (25 mL) and washed with NaHCO₃ solution (25 mL) and water (25 mL). The organic layer was dried (Na₂SO₄) and evaporated in vacuo to give the title compound as an off-white powder (230 mg, 92%). δ_H (DMSO-d₆) 8.15 (1H, dd, J 1.5, 4.7 Hz), 8.04 (1H, dd, J 1.5, 8.1 Hz), 7.70 (1H, dd, J 1.8, 10.1 Hz), 7.57 (1H, d, J 8.4 Hz), 7.33-7.24 (2H, m), 5.26 (2H, br s), 3.47 (2H, t, J6.5 Hz), 3.35 (2H, m), 2.99 (1H, m), 1.98 (1H, m), 1.59 (1H, m). One exchangeable proton was not observed. LCMS (pH 3) RT 1.92 minutes, (ES⁺) 519 (M+H)⁺.

EXAMPLE 5

tert-Butyl [(3S)-1-({2-[(2-fluoro-4-iodophenyl)amino]thieno[2,3-b]pyridin-3-yl}sulfonyl)pyrrolidin-3-yl]carbamate

To a solution of Intermediate 7 (150 mg, 0.24 mmol) and pyridine (0.038 mL, 0.48 mmol) in DCM (5 mL) was added pyrrolidinyl-3(S)-carbamic acid tert-butyl ester (38 mg, 0.48 mmol) and the reaction mixture stirred overnight at room temperature. After this time the reaction mixture was diluted with DCM (35 mL) and washed with 2M HCl (2 x 25 mL) and water (25 mL). After drying (Na₂SO₄) and evaporation in vacuo, the residue was purified by chromatography (SiO₂,25% EtOAc in DCM) to afford the title compound as an off-white solid (132 mg, 89%). δ_H (CDCl₃) 8.98 (1H, s), 8.30 (1H, dd, J 1.6, 4.6 Hz), 8.10 (1H, dd, J 1.6, 8.1 Hz), 7.50 (2H, m), 7.30 (1H, m), 7.27 (1H, dd, J 4.7, 8.2 Hz), 4.55 (1H, br s), 4.11 (1H, s), 3.45 (2H, m), 3.20 (2H, m), 2.10 (1H, m), 1.70 (1H, m), 1.33 (9H, s). LCMS (pH 3) RT 3.56 minutes, (ES⁺) 619 (M+H)⁺.

EXAMPLE 6

3-{[(3S)-3-Aminopyrrolidin-1-yl]sulfonyl}-N-(2-fluoro-4-iodophenyl)thieno[2,3-b]pyridin-2-amine

Example 5 (132 mg, 0.21 mmol) was treated with a 20% solution of TFA in DCM (5 mL). The reaction mixture was stirred for three hours at room temperature before being diluted with DCM (25 mL) and washed with saturated aqueous NaHCO₃ solution (25 mL) and water (25mL). The organic layer was dried (Na₂SO₄) and evaporated in vacuo to give the title compound as an off-white powder (66 mg, 61 %). δ_H (DMSO-d₆) 8.15 (1H, dd, J 1.5, 4.7 Hz), 8.04 (1H, dd, J 1.5, 8.1 Hz), 7.70 (1H, dd, J 1.8, 10.1 Hz), 7.57 (1H, d, J 8.4 Hz), 7.33-7.24 (2H, m), 5.26 (2H, br s), 3.47 (2H, t, J 6.5 Hz), 3.35 (2H, m), 2.99 (1H, m), 1.98 (1H, m), 1.59 (1H, m). One exchangeable proton was not observed. LCMS (pH 3) RT 1.92 minutes, (ES⁺) 519 (M+H)⁺.

EXAMPLE 7

N-(2-Fluoro-4-iodophenyl)-3-(piperazin-1-ylsulfonyl)thieno[2,3-b]pyridin-2-amine hydrochloride

To a solution of Intermediate 9 (60 mg, 0.096 mmol) in 1,4-dioxane (5 mL) was added 4M HCl in 1,4-dioxane (10 mL) and the solution stirred at ambient temperature for 3 hours. The volatiles were then removed in vacuo to give the title compound as an off-white solid (50 mg, quant.). δ_H (DMSO-d₆) 9.13 (1H, s), 9.02 (1H, s), 8.37 (1H, dd, J 1.5, 4.7 Hz), 8.11 (1H, dd, J 1.5, 8.2 Hz), 7.87 (1H, dd, J 1.8, 9.8 Hz), 7.70 (1H, dd, J 1.0, 8.3 Hz), 7.43 (2H, m), 3.40 (4H, m), 3.19 (4H, m). LCMS (pH 10) RT 3.60 minutes, (ES⁺) 519 (M+H)⁺.

EXAMPLES 8 & 9 [DELETED]

EXAMPLE 10

3-(Aminomethyl)-1-({2-[(2-fluoro-4-iodophenyl)aminolthieno[2,3-b]pyridin-3-yl}sulfonyl)azetidin-3-ol

Prepared from Intermediate 7 (170 mg, 0.28 mmol) by the method of Example 3 with Intermediate 11 (100 mg, 0.94 mmol) to give after prep LC the title compound as a white solid (9 mg, 2%). δ_H (DMSO-d₆) 8.24 (1H, s), 8.11 (1H, d, J 4.4 Hz), 7.95 (1H, m), 7.70 (1H, m), 7.57 (1H, m), 7.29-7.22 (2H, m), 5.85 (1H, s), 3.79 (2H, d, J 8.3 Hz), 3.61 (2H, d, J 8.3 Hz), 2.74 (2H, s). Some exchangeable protons were not observed. LCMS (pH 3) RT 2.00 minutes, (ES⁺) 535 (M+H)⁺.

EXAMPLE 11

Ethyl N-{[1-({2-[(2-fluoro-4-iodophenyl)aminolthieno[2,3-b]pyridin-3-yl}sulfonyl)azetidin-3-yl]methyl}-beta-alaninate

To a stirring mixture of Example 2 (160 mg, 0.31 mmol) and N,N-diisopropylethylamine (57 µL, 31 mmol) in DMF (5 mL) was added ethyl acrylate (51 µL, 0.31 mmol) and the mixture allowed to stir for 18 hours. After this time EtOAc (25 mL) was added to the reaction mixture which was then washed with brine (3 x 25 mL), dried (sodium sulfate) and then reduced in vacuo. The resulting oil was purified by column chromatography (SiO₂, 50% DCM in EtOAc) to afford the title compound as a colourless oil (71 mg, 38%). δ_H (CDCl₃) 8.97 (1H, s), 8.30 (1H, dd, J 1.6, 4.7 Hz), 8.12 (1H, dd, J 1.6, 8.2 Hz), 7.51 (2H, m), 7.33 (1H, dd, J 8.7, 8.7 Hz), 7.23 (1H, dd, J 4.7, 8.2 Hz), 4.04 (2H, q, J 7.2 Hz), 3.88 (2H, dd, J 8.0, 8.0 Hz), 3.55 (2H, dd, J 5.6, 8.0 Hz), 2.71 (2H, t, J 6.3 Hz), 2.64 (2H, d, J 7.3 Hz), 2.53 (1H, m), 2.33 (2H, t, J 6.3 Hz), 1.17 (3H, t, J 7.2 Hz). Exchangeable protons were not observed. LCMS (pH 10) RT 3.19 minutes, (ES⁺) 619 (M+H).

EXAMPLE 12

Ethyl N-{[1-(2-[(2-fluoro-4-iodophenyl)amino]thieno[2,3-b]pyridin-3-yl}sulfonyl)azetidin-3-yl]methyl}glycinate

To a stirring mixture of Example 2 (200 mg, 0.39 mmol) and N,N-diisopropyl-ethylamine (68 µL, 42 mmol) in DMF (5 mL) was added ethyl bromoacetate (43 µL, 0.39 mmol) and the mixture allowed to stir for 18 hours. After this time EtOAc (25 mL) was added to the reaction mixture which was then washed with brine (3 x 25 mL), dried (sodium sulfate) and then reduced in vacuo. The resulting oil was purified by column chromatography (SiO₂, 50% DCM in EtOAc) to afford the title compound as a white solid (47 mg, 20%). LCMS (pH 3) RT 2.24 minutes, (ES⁺) 605 (M+H).

EXAMPLE 13

1-({2-[(2-Fluoro-4-iodophenyl)amino]thieno[2,3-b]pyridin-3-}sulfonyl)azetidin-3-ol

Intermediate 3 (150 mg, 0.25 mmol) was dissolved in dichloromethane (6 mL) and triethylamine (75 µL, 0.50 mmol) and 3-hydroxyazetidine HCl salt (55 mg, 0.50 mmol) were added. The reaction mixture was stirred at ambient temperature under nitrogen for 18 hours. Dichloromethane (20 mL) was added and the solution washed with water (10mL), dried (Na₂SO₄) and concentrated in vacuo. The residue was triturated with diethyl ether (10 mL) to remove pentafluorophenol. The crude product was purified by prep HPLC to give after freeze-drying the title compound as a white solid (50 mg, 39%). δ_H (DMSO-d₆) 8.27 (1H, s), 8.21 (1H, d, J 3.5 Hz), 8.00 (1H, dd, J 1.4, 8.3 Hz), 7.76 (1H, dd, J 1.8, 10.0 Hz), 7.61 (1H, d, J 8.3 Hz), 7.37-7.29 (2H, m), 5.73 (1H, br s), 4.36-4.27 (1H, m), 3.95 (2H, dd, J 6.7, 8.4 Hz), 3.54 (2H, dd, J 6.1, 8.4 Hz). LCMS (ES⁺) RT 2.84 minutes, pH 3 method, 506 (M+H)⁺.

EXAMPLE 14

(3R)-1-({2-[(2-Fluoro-4-iodophenyl)amino]thieno[2,3-b]pyridin-3-yl}sulfonyl)pyrrolidin-3-ol

Intermediate 7 (150 mg, 0.25 mmol) was dissolved in dichloromethane (6 mL), and triethylamine (75 µl, 0.50 mmol) and (R)-3-hydroxypyrrolidine (44 mg, 0.50 mmol) were added. The reaction mixture was stirred at ambient temperature under nitrogen for 18 hours. Dichloromethane (20 mL) was added and the solution washed with water (10 mL), dried (Na₂SO₄) and concentrated in vacuo. The residue was triturated with diethyl ether (10 mL), then washed with a further portion of diethyl ether (5 mL) to give the title compound as a white solid (80 mg, 63%). δ_H (DMSO-d₆) 9.08 (1H, br s), 8.33 (1H, d, J 3.4 Hz), 8.17-8.14 (1H, m), 7.84 (1H, dd, J 1.6, 9.9 Hz), 7.67 (1H, d, J 8.4 Hz), 7.49-7.39 (2H, m), 4.93 (1H, br s), 4.25-4.21 (1H, m), 3.41-3.34 (3H, m), 3.15-3.11 (1H, m), 1.93-1.71 (2H, m). LCMS (ES⁺) RT 2.88 minutes, pH 3 method, 520 (M+H)⁺.

EXAMPLE 15

tert-Butyl-[1-({2-[(2-fluoro-4-iodophenyl)amino]thieno[2,3-b]pyridin-3-yl}sulfonyl)-azetidin-3-yl]carbamate

Intermediate 7 (150 mg, 0.25 mmol) was dissolved in dichloromethane (6 mL), and triethylamine (75 µl, 0.50 mmol) and azetidin-3-ylcarbamic acid tert-butyl ester (86 mg, 0.50 mmol) were added. The reaction mixture was stirred at ambient temperature under nitrogen for 18 hours. Dichloromethane (20 mL) was added and the solution washed with water (10 mL), dried (Na₂SO₄) and concentrated in vacuo. The residue was triturated with diethyl ether (10 mL), then washed with a further portion of diethyl ether (5 mL) to give the title compound as a white solid (140 mg, 95%). δ_H (DMSO-d₆) 9.04 (1H, br s), 8.36 (1H, dd, J 1.5, 4.7 Hz), 8.09 (1H, dd, J 1.5, 8.2 Hz), 7.85 (1H, dd, J 1.9, 9.8 Hz), 7.70 (1H, dd, J 1.0, 8.4 Hz), 7.52-7.41 (3H, m), 4.22-4.19 (1H, m), 3.96 (2H, t, J 7.5 Hz), 3.63 (2H, t, J 7.5 Hz), 1.31 (9H, s). LCMS (ES⁺) RT 3.48 minutes, pH3 method, 605 (M+H)⁺.

EXAMPLE 16

3-[(3-Aminoazetidin-1-yl)sulfonyl]-N-(2-fluoro-4-iodophenyl)thieno[2,3-b]pyridin-2-amine

Example 15 (125 mg, 0.21 mmol) was dissolved in dichloromethane (3 mL). TFA (2 mL) was added and the reaction mixture was stirred at r.t. for 5 hours. After concentrating in vacuo, the residue was partitioned between ethyl acetate (100 mL) and sat. sodium carbonate solution (100 mL). The organic phase was dried (Na₂SO₄), and concentrated in vacuo to give the title compound as an off-white solid (65 mg, 63%). δ_H (DMSO-d₆) 8.33 (1H, dd, J 1.6, 4.7 Hz), 8.08 (1H, dd, J 1.6, 8.2 Hz), 7.83 (1H, dd, J 1.9, 9.9 Hz), 7.70-7.66 (1H, m), 7.50-7.39 (2H, m), 4.74 (3H, br s), 3.94-3.89 (2H, m), 3.64-3.55 (1H, m), 3.41-3.33 (2H, m). LCMS (ES⁺) RT 2.67 minutes, pH 3 method, 505 (M+H)⁺.

Claims

A compound of formula (I), or a pharmaceutically acceptable salt, solvate or N-oxide thereof:
wherein
R¹ represents hydrogen, halogen or C_1-6 alkyl;
R² represents halogen or C_1-6 alkyl;
R³ represents -SO₂NR^bR^c; and
R^b and R^c, when taken together with the nitrogen atom to which they are both attached, represent azetidin-1-yl, pyrrolidin-1-yl, piperidin-1-yl, morpholin-4-yl, thiomorpholin-4-yl, piperazin-1-yl, homopiperidin-1-yl, homomorpholin-4-yl or homopiperazin-1-yl, any of which groups may be optionally substituted by one or more substituents selected from C_1-6 alkyl, hydroxy, hydroxy(C_1-6)alkyl, C_1-6 alkoxy, C_1-6 alkoxy(C_1-6)alkyl, amino(C_1-6)alkyl, (amino)(hydroxy)(C_1-6)alkyl, halogen, oxo, C_2-6 alkylcarbonyl, carboxy, carboxy(C_1-6)alkyl, C_2-6 alkoxycarbonyl, C_2-6 alkoxycarbonyl-(C_1-6)alkyl, di(C_1-6)alkylhydrazinylcarbonyl, amino, C_1-6 alkylamino, di(C_1-6)alkylamino, C_2-6 alkylcarbonylamino, C_2-6 alkoxycarbonylamino, C_2-6 alkoxycarbonylamino(C_1-6)-alkyl, C_2-6 alkoxycarbonyl(C_1-6)alkylamino(C_1-6)alkyl, aminocarbonylamino, aminocarbonyl, C_1-6 alkylaminocarbonyl, di(C_1-6)alkylaminocarbonyl, aminosulfonyl, C_1-6 alkylsulfonyl and C_1-6 alkylaminocarbonyl(C_1-6)alkyl.
A compound as claimed in claim 1 wherein the cyclic moiety -NR^bR^c represents azetidin-1-yl, pyrrolidin-1-yl or piperidin-1-yl, any of which groups may be optionally substituted by one or more substituents as defined in claim 1.
A compound as claimed in claim 1 or claim 2 wherein the cyclic moiety -NR^bR^c is unsubstituted, or substituted by one or two substituents as defined in claim 1.
A compound as claimed in any one of the preceding claims wherein the substituents on the cyclic moiety -NR^bR^c are selected from hydroxy, amino, amino-(C_1-6)alkyl, C_2-6 alkoxycarbonylamino and C_2-6 alkoxycarbonyl(C_1-6)alkylamino-(C_1-6)alkyl.
A compound as claimed in claim 4 wherein the substituents on the cyclic moiety -NR^bR^c are selected from hydroxy, amino, aminomethyl, tert-butoxycarbonyl-amino, ethoxycarbonylmethylaminomethyl and ethoxycarbonylethylaminomethyl.
A compound as claimed in claim 1 wherein the cyclic moiety -NR^bR^c represents 3-hydroxyazetidin-1-yl, 3-aminoazetidin-1-yl, 3-(aminomethyl)azetidin-1-yl, 3-(aminomethyl)-3-hydroxyazetidin-1-yl, 3-(tert-butoxycarbonylamino)azetidin-1-yl, 3-(ethoxycarbonylmethylaminomethyl)azetidin-1-yl, 3-(ethoxycarbonylethylaminomethyl)-azetidin-1-yl, pyrrolidin-1-yl, 3-hydroxypyrrolidin-1-yl, 3-aminopyrrolidin-1-yl, 3-(tert-butoxycarbonylamino)pyrrolidin-1-yl or piperazin-1-yl.
A compound as claimed in claim 1 represented by formula (II), and pharmaceutically acceptable salts, solvates and N-oxides thereof:
wherein
R¹² represents halogen; and
R³ is as defined in claim 1.
A compound as claimed in claim 7 wherein R¹² represents bromo or iodo.
A compound as claimed in claim 8 wherein R¹² is iodo.
A compound as claimed in claim 1 selected from the following:
N-(2-fluoro-4-iodophenyl)-3-(pyrrolidin-1-ylsulfonyl)thieno[2,3-b]pyridin-2-amine;

3-{[3-(aminomethyl)azetidin-1-yl]sulfonyl}-N-(2-fluoro-4-iodophenyl)thieno[2,3-b]-pyridin-2-amine;

tert-butyl [(3R)-1-({2-((2-fluoro-4-iodophenyl)amino]thieno[2,3-b]pyridin-3-yl}-sulfonyl)pyrrolidin-3-yl]carbamate;

3-{[(3R)-3-aminopyrrolidin-1-yl]sulfonyl}-N-(2-fluoro-4-iodophenyl)thieno[2,3-b]-pyridin-2-amine;

tert-butyl [(3S)-1-({2-[(2-fluoro-4-iodophenyl)amino]thieno[2,3-b]pyridin-3-yl}sulfonyl)-pyrrolidin-3-yl]carbamate;

3-{[(3S)-3-aminopyrrolidin-1-yl]sulfonyl}-N-(2-fluoro-4-iodophenyl)thieno[2,3-b]-pyridin-2-amine;

N-(2-fluoro-4-iodophenyl)-3-(piperazin-1-ylsulfonyl)thieno[2,3-b]pyridin-2-amine hydrochloride;

3-(aminomethyl)-1-({2-[(2-fluoro-4-iodophenyl)amino]thieno[2,3-b]pyridin-3-yl-sulfonyl)azetidin-3-ol;

ethyl N-{(1-({2-[(2-fluoro-4-iodophenyl)amino]thieno[2,3-b]pyridin-3-yl}sutfonyl)-azetidin-3-yl]methyl}-beta-alaninate;

ethyl N-{[1-({2-[(2-fluoro-4-iodophenyl)amino]thieno[2,3-b]pyridin-3-yl}sulfonyl)-azetidin-3-yl]methyl glycinate;

1-({2-[(2-fluoro-4-iodophenyl)amino]thieno[2,3-b]pyridin-3-yl} sulfonyl)azetidin-3-ol;

(3R)-1-({2-[(2-fluoro-4-iodophenyl)amino]thieno[2,3-b]pyridin-3-yl}sulfonyl)pyrrolidin-3-ol;

tert-butyl-[1-({2-[(2-fluoro-4-iodophenyl)amino]thieno[2,3-b]pyridin-3-yl}sulfonyl)-azetidin-3-yl]carbamate; and

3-[(3-aminoazetidin-1-yl)sulfonyl]-N-(2-fluoro-4-iodophenyl)thieno[2,3-b]pyridin-2-amine.
A pharmaceutical composition comprising a compound of formula (I) as defined in claim 1, or a pharmaceutically acceptable salt, solvate or N-oxide thereof, in association with a pharmaceutically acceptable carrier.
The use of a compound of formula (I) as defined in claim 1, or a pharmaceutically acceptable salt, solvate or N-oxide thereof, for the manufacture of a medicament for the treatment and/or prevention of disorders for which the administration of a selective MEK inhibitor is indicated.
A compound of formula (I) as defined in claim 1, or a pharmaceutically acceptable salt, solvate or N-oxide thereof, for use in therapy.
A compound of formula (I) as defined in claim 1, or a pharmaceutically acceptable salt, solvate or N-oxide thereof, for use in the treatment and/or prevention of an inflammatory, autoimmune, cardiovascular, proliferative or nociceptive condition.
A compound of formula (I) as defined in claim 1, or a pharmaceutically acceptable salt, solvate or N-oxide thereof, for use in the treatment and/or prevention of an oncological condition.